Although increasingly more mental health services worldwide have implemented Illness Management and Recovery (IMR), the evidence-based psychosocial program, research has shown the program’s low rate of sustainability over time. Thus, knowledge about what professionals perceive to be important for sustaining IMR program is needed. The aim of this study was to explore the perspectives of professionals who work at sites that have offered IMR for at least 6 years regarding what they perceive as being crucial for sustaining IMR program. Focus group interviews were conducted with 36 mental health care professionals in Norway who have experience with providing group-based IMR treatment to people with severe mental illness. Data from the interviews were subjected to reflexive thematic analysis. Three factors were determined to be essential to promoting the sustainable practice of IMR: anchoring in the organization, access to training and guidance, and the allocation of time for preparation and reflection. Achieving IMR’s long-term sustainability requires building joint ownership and a shared future vision for the program within the administering organization. To motivate professionals to continue providing IMR treatment, sufficient time and space are needed in order to provide professionals with training, continued guidance and supervision, and time to reflect on their clinical practice. Moreover, engaged leadership is crucial to facilitating professionals’ access to required resources.